The overall objective of this project is to develop novel methods that induce protective immunity against biological threat organisms. Because of recent advances in vaccine and adjuvant technologies, plus increased understanding of the innate immune system, it is possible to overcome problems that have hindered effective immune protection, particularly against aerosolized agents. Since the members of our group have the greatest experience with Yersinia, we will use Yersinia pestis as our model. However, our results will be applicable to all gram-negative biological warfare agents under investigation in this RCE. Our first three aims will focus on protection against Y. pestis in murine and primate infection models. After that, the technologies that are most effective against this organism will be applied to animal models for Francisella tularensis and Burkholderia pseudomallei. Our four specific aims include: 1. To assess the efficacy of innate immune system stimulation to protect against aerosolized Y. pestis. 2. To assess the ability of novel adjuvants to enhance protection with Y. pestis subunit and live attenuated vaccine candidates. 3. To identify genetic loci affecting Y. pestis virulence for development of an attenuated vaccine 4. To apply the knowledge obtained in these Y. pestis studies to enhance innate and specific immunity towards Burkholderia pseudomallei and Francisella tularensis. A variety of novel subunit vaccines and live attenuated vaccine strains will be used to induce specific immunity against Y. pestis. These vaccines will be used with and without the additional exposure of the animals to agents known to stimulate the innate immune response. Several promising innate immunity stimulators include SEC1m, a nontoxic derivative of a staphylococcal superantigen, monophosphoryl Lipid A, and related mimetic compounds produced by our collaborators at Corixa Corporation. Encouraging preliminary results showed these compounds protect against pathogens in several animal models, including aerosol challenges. A strength of our proposal is that we have the ability to conduct large scale screening of various immunization strategies. All compounds and vaccine strategies will be screened initially in mice in the BLS-3 facility at the University of Idaho. Once promising compounds are identified, we will move these experiments to the Pulmonary and Primate Cores at the University of Washington where larger scale testing can be conducted. This will allow us to determine the most effective dose and timing regimens, and to assess whether protection observed in mice can be reproduced in Macaca nemestrina monkeys.